Welcome to the AC Tropical Fish aquarium forum. Our aquarium forum is the place to discuss any aquarium related issue in a friendly environment. Our aquarium forum welcomes aquarists of all levels from beginners to experts. Please ask a question in the how to section of our forum or read the FAQ section if you have any questions. register to and become a part of our friendly aquarium forum community today.

CO2/O2 Balance... That's the Question

0

First of all, thanks for reading! My question is of course regarding the never ending task of maintaining a healthy balance of CO2 and O2. So for a little back information, I have a 36 gallon tank with 3 sword plants, a ribbon plant, and an unknown cool grass like plant with defined leaves with a 62 watt T5 light. Fish are: 6 platties, 8 neon/glowlight tetras, 2 cory cats. Sidenote, I want to add a few nerite snails for algae control. So far, so good, plants seem to be doing well, but I am sure that adding some CO2 would help them even more. My fear is adding to much and hurting the fish (which is priority over the plants even though I love the plants and want to see them get big). I am wondering if I should run a bubbler and some CO2. I am very new at this (4 weeks in) and would love ANY advice I can get. Not sure if I am on the right track or not. Thanks so much for the read and any advice!

That does sound like higher lighting levels for a 36 gallon tank, so you might need pressurized CO2. But I;m not too sure about that to be honest with you

Most people with only run the CO2 during the day when the lights are on and the plants will be using CO2. That way you can aviod a build-up of CO2. That might be a approach worth looking into. You might need more plants in your tank to make it work OK. I'm pretty new to using CO2 myself

If you take your time to do the research FIRST, you can successfully set-up and keep ANY type of aquarium with ease."Not using a quarantine tank is like playing Russian roulette. Nobody wins the game, some people just get to play longer than others." - Anthony CalfoFishless CycleCycling with FishMarine Aquarium Info [URL="http://saltwater.aquaticcommunity.com/"]

if you are running a pressurized CO2 system, then you can accurately aim for a certain concentration. anything above 10 ppm and below 30 ppm (above 35 can be lethal to fish) should work. there are many ways
to check CO2 levels such as CO2/pH charts and drop checkers. if you are going with DIY CO2, then there is very little chance of actually reaching a concentration that could potentially harm fish. a common misconception is that adding carbon dioxide to a tank will displace oxygen. this is not true. oxygen levels in your tank will remain same (or even increase due to the plant's increased metabolism) but there simply will be CO2 added to the mix.
I am not experienced with pressurized CO2(the gas tanks) but if going DIY, a link i have found useful is http://www.qsl.net/w2wdx/aquaria/diyco2.html

Just remember at night, plants use oxygen and produce none; as such, best not to run an active CO2 system unless it is controled by a sesnor. If no sensor and no easy way to turn it off at night, just use an air pump/bubbler on a timer for night operation.

Last edited by Cermet; 03-21-2013 at 08:25 PM.

Knowledge is fun(damental)

A 75 gal with eight Discus, fake plants, and a lot of wood also with sand substrate. Clean up crew is down to just two Sterba's Corys. Filters: continuous new water flow; canister w/UV, in-tank algae scrubber!! Finally, junked the nitrate removal unit from hell.

Thank you guys for the feedback! I am worried there is not enough oxygen in my water as my fish seem to be gasping for air. Should I ru CO2 during the day and oxygen at night? Or oxygen all the time? Thanks again for the help!

I see no reason not to use a bubble wand or airstone at night - just let the timer turn it on/off when needed. As for the day, something is wrong with your delivery system if the fish are struggling for oxygen.

If you think that is the problem with CO2 displacing oxygen during the day, use a needle valve and regulate the rate entering the tank's diffuser. You could also side vent off excessive pressure if that is an issue by using another needle valve. In no case will running an airstone at night help fish during the day. Running an airstone during the day defeats the point of a CO2 system - just cut back on the amount.

Knowledge is fun(damental)

A 75 gal with eight Discus, fake plants, and a lot of wood also with sand substrate. Clean up crew is down to just two Sterba's Corys. Filters: continuous new water flow; canister w/UV, in-tank algae scrubber!! Finally, junked the nitrate removal unit from hell.

If the tank is 4 weeks old and there's gasping I'm wondering if it's cycled.

Anyway, with this much light a pressurized system would be the best choice. Also get a drop checker to allow you to monitor what's going on. Start slowly and work your way up. An airstone at night makes sense, during the day it will actually cause you to lose some co2.
If you do go the co2 route be prepared to start dosing ferts as well. Start reading up on the EI method.

Oh, and my personal point of view. Co2 is not necessary for most plants. You can run fine without and still get benefits from the high lights with proper fertilizing. Just takes a bit longer for things to grow.